Skip unneeded ironic jobs on stable branches
Skip unneeded ironic jobs on stable branches

This patch skip running the following Ironic jobs on stable mitaka|newton
as they are available starting from Ocata only:

  * ironic-ipa-wholedisk-agent_ipmitool-tinyipa-multinode-ubuntu-xenial
  * ironic-ipa-wholedisk-pxe_snmp-tinyipa-ubuntu-xenial
  * ironic-ipa-partition-pxe_snmp-tinyipa-ubuntu-xenial

Change-Id: I345d4999a74bb8019d6bdc8604239419277506cf

openstack-infra/project-config,openstack-infra/project-config